Tag Archives: oceans

The search for sustainable plastics

By Phil McKenna, Ensia 
July, 2015


As petroleum-based polymers foul our oceans and litter our lives, researchers seek more environmentally friendly ways to meet demand for durable, versatile materials. Photo courtesy of Algalita Foundation

The fate of the world’s oceans may rest inside a stainless steel tank not quite the size of a small beer keg. Inside, genetically modified bacteria turn corn syrup into a churning mass of polymers that can be used to produce a wide variety of common plastics.

“It’s a bit like making yogurt,” says Oliver Peoples, chief scientific officer of  Metabolix, Inc.

The Cambridge, Massachusetts–based U.S. company where bioplastics take shape in laboratory-scale fermentation chambers is one of a growing number of businesses and institutions working to develop cost-competitive, more environmentally friendly replacements for conventional plastics, which are made from fossil fuels, fail to decompose and are turning our oceans into seas of floating plastic.

“We’ve seen this huge increase in production in plastic that results in an increase in the waste stream as well,” says Jenna Jambeck, an environmental engineering faculty member at the University of Georgia. “Unlike material that biodegrades, plastic has all of these issues. It easily travels into waterways, it physically fragments into smaller pieces which are extremely hard or impossible to collect, and [it tends to] absorb chemical contaminants that are already in the environment.”

Some 4.8 million to 12.7 million metric tons (5.3 million to 14 million tons) of plastic, or up to 4 percent of the roughly 300 million metric tons (330 million tons) of plastic produced each year, entered the ocean as trash in 2010. The figure is expected to increase 10-fold in the next decade as more plastic is produced and subsequently evades waste management and recycling efforts, according to a study Jambeck and colleagues published earlier this year in the journal Science.

What effect all this plastic has on living things, including humans, remains unclear. A number of recent studies show that chemicals in small bits of plastic, and even the plastic bits themselves, can accumulate in birds, fish and other marine life. Laboratory testing has shown the chemicals that comprise them can cause adverse health effects, including liver damage and endocrine disruption through altered gene expression. Whether similar effects occur outside the laboratory or whether they extend up the food chain to people who eat marine organisms remains unknown, yet both seem entirely plausible.

And that’s not all. Plastics are notorious in the greenhouse gas department as well. Roughly 8 percent of the petroleum used worldwide each year goes to make plastic directly or to power the plastic manufacturing processes, according to a recent report by the Worldwatch Institute.

“Even though people feel like they would like to use less plastic rather than more, the fact of the matter is that plastics are modern materials that make cars lighter, purify water and add tremendous benefit to health and security applications.” — Marc HillmyerWhy not just reduce our use? For one thing, plastics are incredibly versatile, meeting a spectrum of needs for flexibility, cost and other parameters that substitute materials would be hard put to match. Not only that, but substitute materials present their own adverse environmental, social and health impacts.

“Even though people feel like they would like to use less plastic rather than more, the fact of the matter is that plastics are modern materials that make cars lighter, purify water and add tremendous benefit to health and security applications,” says Marc Hillmyer, director of the Center for Sustainable Polymers at the University of Minnesota in Minneapolis.

In other words, there are solid reasons for pursuing more sustainable alternatives to conventional plastics — namely, plant-based plastics. Such so-called bioplastics are able to degrade, dramatically reducing the risk that they’ll end up polluting land or sea. They also lower our dependence on fossil fuels, reducing plastic’s carbon footprint. Greenhouse gas emissions associated with bioplastics are 26 percent lower than those associated with conventional plastic, according to a recent life-cycle analysis of corn-based and petroleum-based plastic by researchers at Michigan State University.

Emerging Alternatives

Finding non-petroleum-based, decomposable alternatives to today’s plastics, however, isn’t easy. Plastic made from corn, sugarcane or other plant-based material isn’t necessarily degradable, and getting degradation to occur when you want it to can be difficult.

“You don’t want your plastic bag to degrade while you are using it,” Hillmyer says. “On the other hand you want it to degrade rapidly when put into another environment.”

While chemists have had difficulty reformulating petroleum-based plastics so that they can degrade, a number of bio-based, degradeable alternatives are emerging.

Despite these and other recent successes, bioplastics remain a tiny fraction of the industry as a whole. Natureworks, a company based in Minnetonka, Minnesota, is one of the world’s leading manufactures of bioplastics. The company makes polylactic acid, or PLA, a biodegradable plastic it sources from cornstarch and makes into a wide range of consumer products — including single-use flatware, cups and packaging — that decompose at the end of their useful life. The company’s initial production facility in Blair, Nebraska, came online in 2002 and can produce 140,000 metric tons (150,000 tons) of PLA per year. The company recently announced plans to open a second plant in Southeast Asia that would use sugarcane as its feedstock.

Another leading manufacturer of bioplastic is the Coca-Cola Company, which in 2009 launched PlantBottle, a drink bottle made from polyethylene terephthalate —PET — that contains up to 30 percent biobased material. The bottles are not degradable but, unlike most biobased plastics, can be recycled along with conventional PET, a commonly recycled plastic. Since 2009 the company has produced 35 billion of its original PlantBottles. In June 2015 the company unveiled a new version that is 100 percent biobased.

Despite these and other recent successes, bioplastics remain a tiny fraction of the industry as a whole. The materials are well suited for single use products such as spoons and bottles where consumers are willing to pay a premium for more sustainable products. High durability, less-visible applications — for example, water pipes made of PVC that are commonly used in residential and commercial plumbing — are still made entirely of conventional plastic. In total, less than 0.5 percent of all plastic comes from non-petroleum sources, according to the Society of the Plastics Industry, an industry trade group based in Washington, D.C.

Government regulation, however, is leading to the increased use of bioplastics. In 2014 Illinois banned microbeads, tiny plastic abrasives commonly used in facial scrubs, shampoo and toothpaste, due to concerns about environmental degradation in the Great Lakes. At less than one millimeter in diameter, microbeads are too small to be filtered by sewage treatment systems and have been found in both freshwater and marine environments.

With a federal ban on microbeads expected, Metabolix partnered with Honeywell in March to produce a biodegradable alternative to microbeads The microbeads the two companies are developing are made from Polyhydroxyalkanoates, or PHA, a bio-based plastic that is more expensive but also more versatile than PLA. The microbeads the two companies are developing are made by fermenting cornstarch, though they could also be made from non-food crops such as switchgrass. PHA microbeads will degrade into carbon dioxide and water in a matter of months at the same rate as cellulose or paper, Peoples says.

Around the Down Sides

As we increase our reliance on plastics sourced from crops such as corn or sugarcane, we could inadvertently introduce new environmental concerns. A recent study in the journal Cleaner Production noted bioplastics grown from agricultural feedstocks use significant amounts of water, pesticides and fertilizers that can cause air and water pollution and compete for land with crops grown for food.

One possible way to get around the down sides of plant-based plastics while still reducing dependence on petroleum is to use CO2 as a feedstock instead. Novomer, a company spun out from research at Cornell University in Ithaca, New York, is turning waste CO2 from ethanol production plants into plastic. The company makes polyols — polymers used to make flexible foam found in mattresses, seat cushions and insulation, as well as a range of specialty coatings and sealants.

“If your mattress was made with our material, it would be roughly 22 percent by weight carbon dioxide,” says Peter Shepard, Novomer’s executive vice president of polymers. It takes a greenhouse gas that is a waste material and turns it into a valuable product.”

Typically CO2 is too inert to react with other compounds, making its use in plastics or other applications difficult. Geoffrey Coates, a chemistry professor at Cornell University in Ithaca and a co-founder of Novomer, developed a catalyst that increased the reactivity of CO2 while simultaneously slowing down the reactivity of another key polyol ingredient — making it easier to incorporate CO2 into the resulting polymer.

“It’s like if you have kids and you give them pizza and broccoli and you tell them every time you take a bite of pizza you have to take a bite of broccoli,” says Coates, who is also a member of the Center of Sustainable Polymers.

The biggest challenge for bioplastics is that they are competing against conventional plastics, incredibly inexpensive materials that have been honed for the past 60 years, Scheer says.The polyols made by Novomer are degradable but lose their degradability when combined with petroleum-based chemicals to make foam.

Though the company is currently focused on making foams and sealants, Shepard says Novomer’s CO2-based polymers could be used to make degradable plastics with a CO2 content as high as 50 percent.

Biggest Challenge

Despite strong growth in recent years, some say bioplastics haven’t lived up to their potential.

“The bioplastics industry has not been able to create polymers that are attractive enough in terms of pricing and in terms of properties that will make the world willing to change,” says Frederick Scheer, the former CEO of Cereplast, a once-leading bioplastics company that declared bankruptcy in 2014.

The biggest challenge for bioplastics is that they are competing against conventional plastics, incredibly inexpensive materials that have been honed for the past 60 years, Scheer says.

“People are somewhat conscious of the environmental impact of oil-based materials that will not biodegrade, but they are not willing to spend the extra dollars to push [new] types of materials,” he says.

Competition with petroleum-based plastic has only intensified over the past year as the price of oil has dropped in half. “In order to be competitive with traditional oil-based material we needed the price of oil to be somewhere around $130, $140 a barrel,” Scheer says. “Clearly, at $50 a barrel we are far away from being able to compete.”

Scheer says the capacity to make all of the world’s plastic from non-petroleum sources exists, but to do so would require significant government support. “It will have to be driven by regulation that will force the cost of plastic and cost of oil to be substantially higher than it is right now,” he says.

Polyethylene Competitor?

If sustainable plastics that reduce our dependence on fossil fuels and degrade at the end of their useful life are going to go mainstream, they will have to be able to sub in not only for microbeads, foam and other specialty applications but also for thermoplastics — low-cost, shapeable polymers that comprise more than 80 percent of the hundreds of millions of tons of plastic produced each year.

Coates is now working on a new biopolymer with properties comparable to or perhaps better than polyethylene, the most widely produced thermoplastic used to make everything from trash bags to water bottles to plastic toys.

Even a thin layer of polyethylene is incredibly strong, making, for example, mailing envelopes that are nearly impossible to open without scissors or milk jugs that don’t break when dropped on the floor. “Most of that is because it’s a semicrystalline material,” Coates says. “The [polymer] chains pack next to each other in a very tight and specific fashion that overall, gives pretty impressive properties.”

In a 2014 study published in the Journal of the American Chemical Society, Coates and colleagues at Cornell described a new material with a semicrystalline structure that is made from a sugar feedstock and has properties similar to polyethylene, yet is better able to decompose at the end of its useful life.

“It doesn’t happen overnight, but I think there are certain positive [indications that it] could be a real competitor for a plastic like polyethylene,” Hillmyer says.

The new material, known as poly(polypropylene succinate), hasn’t been tested to see how quickly it would decompose in a landfill or marine environment. But based on its composition, Coates says, it should begin to degrade in water after several months, a time period that would exceed the useful life of most single use products. Poly(polypropylene succinate) breaks down into propylene glycol and succinic acid, nontoxic materials that are further reduced to CO2 and water when ingested by microbes.

“If you had to eat polymer degradation products, these would be the ones you want,” Coates says.

It’s unlikely that poly(polypropylene succinate) will ever cost less on a pound-for-pound basis than conventional polyethylene, but its unique crystalline structure suggests it could perform better than its petroleum counterpart. If so, bioplastics manufacturers may someday be able to compete with today’s plastics industry by making things like milk jugs with significantly less material than petroleum-based plastics.

Uphill Battle

Short of sweeping government regulations that place a price on carbon or require all plastics to biodegrade, bioplastics will have to find ways to outcompete conventional plastics if they are ever going to fill more than niche applications.

It’s an uphill battle — but one that another once-niche product, the solar panel, is increasingly winning.

In 2007 solar power made up less than 0.1 percent of U.S. electricity generation. Thanks to ingenuity and innovation, the price of photovoltaic modules has dropped from US$4 per watt to US$0.50 per watt, making solar the fastest growing source of electricity in the country.

Might those working on bioplastics see a similar sea change? Ultimately, a lot will likely ride not only on how well their products break down, but on how much they can break down conventional plastic’s competitive edge.View Ensia homepage

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This piece was originally published on Ensia, a magazine showcasing environmental solutions in action, under the Institute on the Environment at the University of Minnesota with support from major foundations and private individuals. 

Editor’s note: Marc Hillmyer is a resident fellow of the University of Minnesota Institute on the Environment, which publishes Ensia.

Related on F&O:

The World’s Largest Electronic Waste Dump, photo essay by Tyrone Siu, Reuters, July, 2015
Chris Wood: Natural Security, Facts and Opinions column  (paywall)


Phil McKenna is a freelance writer interested in the convergence of fascinating individuals and intriguing ideas. He primarily writes about energy and the environment with a focus on the individuals behind the news. His work appears in The New York Times, Smithsonian, WIRED, Audubon, New Scientist, Technology Review, MATTER and NOVA, where he is a contributing editor. 






Facts and Opinions is a boutique journal, of reporting and analysis in words and images, without borders. Independent, non-partisan and employee-owned, F&O is funded by you, our readers. We do not carry advertising or “branded content,” or solicit donations from foundations or causes. Support us with a subscription (click here for our subscribe page) or a donation:



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Does deep Atlantic heating account for global warming hiatus?

A humpback whale feeding off the coast of Newfoundland on Canada's Atlantic coast. Photo by Greg Locke © 2014

A humpback whale feeding off the coast of Newfoundland on Canada’s Atlantic coast. Photo by Greg Locke © 2014

By Richard AllanUniversity of Reading, The Conversation
August 21, 2014

There seem to have been a dozen or so explanations for why the Earth’s surface has warmed at a slower rate over the past 15 years compared to earlier decades. This is perhaps not so surprising given the complexity of the climate system – the world’s best detectives will inevitably struggle to disentangle the factors which influence every lump and bump in the surface temperature record.

However, recent research implicates natural changes in the Pacific and Atlantic oceans as the prime culprits. Just as the apparently random motions in a river’s flow can shift before our eyes from one minute to the next, the gradual sloshing about of our vast ocean waters can influence Earth’s climate from one year to the next and from one decade to the next.

It is clear that natural variability has and always will influence the climate. In addition to chaotic ocean fluctuations, changes in the brightness of the sun and variations in the frequency and intensity of volcanic eruptions (which cool the planet temporarily with sunlight-reflecting aerosol particles) influence the surface temperature. The recent Intergovernmental Panel on Climate Change working report found that these natural factors have contributed toward the slowing rate of surface warming since 1998.

However, recent measurements of ocean temperature made by thousands of automated buoys and observations of Earth’s radiative energy budget by satellite instruments indicate that heating has continued at a rate equivalent to every person worldwide using about 20 kettles each to continuously boil the oceans. This is consistent with what is expected from the rising atmospheric concentrations of greenhouse gases due to human activity. If anything, Earth’s heating rate increased between the 1985-1999 and 2000-2012 periods, despite a slowing in the rate of surface warming.

Observed and simulated changes in Earth’s heating rate since 1985. Image by Allan et al., author provided

Observed and simulated changes in Earth’s heating rate since 1985. Image by Allan et al., author provided

So, how is it possible for increased heating to not directly correspond with surface warming? The Earth’s heating is caused by an imbalance between the amount of absorbed sunlight and the heat emitted back to space. This surplus of heat is primarily absorbed by the oceans since they command the lion’s share of storage capacity compared with other parts of the climate system such as the land, the atmosphere or the cryosphere (ice and snow). This large heat capacity of water is noticable from the amount of time it takes to heat up your pan of vegetables. And there is a lot of water in the oceans; nearly a fifth of a cubic kilometre of water for each person on the planet.

Crucially, the temperature at the Earth’s surface depends upon where this heat is deposited in the oceans. If the upper levels warm, so too will the atmosphere above. However, if ocean circulations cause more heat to be drawn down to deeper depths (or less heat to be moved upward toward the sea surface) then surface temperatures will reflect this. Recent research has implicated our largest ocean, the Pacific, as the most likely mechanism for subducting heat to deeper levels.

Indeed, atmospheric and ocean conditions in the Pacific have been unusual in the past decade and computer simulations show that decades of slow surface warming despite rising greenhouse gas concentrations are associated with increased heating below 300m depth. The mechanisms for heat absorption are less clear; the simulations show that similar patterns appearing to originate from the Pacific are associated with the draw-down of heat in the North Atlantic and Southern Ocean as well as the Pacific.

New research published in Science now shifts the focus towards the Atlantic Ocean. Xianyao Chen and Ka-Kit Tung of the University of Washington show that heating from rising greenhouse gas concentrations has preferentially warmed the ocean’s 300-1500m layer since about 2000, thereby depriving the upper layers of this surplus heat and causing surface warming to slow.

The authors say these changes are part of a natural cycle of knock-on effects, involving ocean circulation responses to changes in how salty (and therefore dense) the upper Atlantic Ocean layers are. This cycle is thought to last around 30 years, contributing a sustained cooling effect then a warming influence on surface temperatures; when combined with steady heating from greenhouse gas increases this leads to a “staircase” effect of stable temperatures followed by rapid warming.

They argue the previous focus on the Pacific was based upon simulations that were unable to fully capture the intricacies of the Atlantic Ocean circulation. An observed decline in the North Atlantic Ocean circulation over recent years has also been identified as part of a longer-term shift based upon evidence from computer simulations.

The changes in ocean circulation have also been shown to influence seasonal extremes and, based upon the proposed Atlantic mechanism, may persist for another decade before rapid warming is re-established. However, the nature of internal ocean fluctuations means it is difficult to pin down timings with any confidence.

While it is human nature to seek a single cause for notable events, in reality the complexity of the climate system means that it is unlikely there is one simple reason for any extreme weather event or a decade of unusual climatic conditions. Nevertheless, the recent hiatus in global surface warming has encouraged scientists to further scrutinise and learn in even finer detail than before the workings of our climate system.

The ConversationCreative Commons

Richard Allan receives funding from the Natural Environment Research Council.

This article was originally published on The Conversation. Read the original article.

Further reading on F&O:

Environmental Assessments Include Climate, by Chris Wood (Frontlines post) 
A few words about an old friend, Natural Security column by Chris Wood (paywall) 
The point of no return, Natural Security column by Chris Wood (paywall) 
The Ugly Oil Sands Debate, by Tzeporah Berman (column) 
Oceans sickened by domestic disease, climate change by Deborah Jones (Dispatch, paywall)
Ignorance of science worsens global crises, warn researchers.  By Deborah Jones (Dispatch, paywall)

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